Metamorphic Wurm

Threshold — Metamorphic Wurm gets +4/+4 as long as seven or more cards are in your graveyard.

Island

Springing Tiger

Threshold — Springing Tiger gets +2/+2 as long as seven or more cards are in your graveyard.

Crashing Centaur

{G}, Discard a card: Crashing Centaur gains trample until end of turn.
Threshold — As long as seven or more cards are in your graveyard, Crashing Centaur gets +2/+2 and has shroud. (It can't be the target of spells or abilities.)

Sylvan Might

Target creature gets +2/+2 and gains trample until end of turn.
Flashback {2}{G}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Overrun

Creatures you control get +3/+3 and gain trample until end of turn.

Careful Study

Timberland Ruins

Timberland Ruins enters tapped.
{T}: Add {G}.
{T}, Sacrifice Timberland Ruins: Add one mana of any color.

Repel

Put target creature on top of its owner's library.

Muscle Burst

Target creature gets +X/+X until end of turn, where X is 3 plus the number of cards named Muscle Burst in all graveyards.

Stone-Tongue Basilisk

Whenever Stone-Tongue Basilisk deals combat damage to a creature, destroy that creature at end of combat.
Threshold — As long as seven or more cards are in your graveyard, all creatures able to block Stone-Tongue Basilisk do so.

Werebear

{T}: Add {G}.
Threshold — Werebear gets +3/+3 as long as seven or more cards are in your graveyard.

Cephalid Looter

{T}: Target player draws a card, then discards a card.

Twigwalker

{1}{G}, Sacrifice Twigwalker: Two target creatures each get +2/+2 until end of turn.

Ivy Elemental

Ivy Elemental enters with X +1/+1 counters on it.

Nimble Mongoose

Shroud (This creature can't be the target of spells or abilities.)
Threshold — Nimble Mongoose gets +2/+2 as long as seven or more cards are in your graveyard.

Peek

Look at target player's hand.
Draw a card.

Roar of the Wurm

Create a 6/6 green Wurm creature token.
Flashback {3}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Krosan Avenger

Trample
Threshold — {1}{G}: Regenerate Krosan Avenger. Activate only if seven or more cards are in your graveyard.

Predict

Choose a card name, then target player mills a card. If a card with the chosen name was milled this way, you draw two cards. Otherwise, you draw a card.

Seafloor Debris

Seafloor Debris enters tapped.
{T}: Add {U}.
{T}, Sacrifice Seafloor Debris: Add one mana of any color.

Forest

Seton's Desire

Enchant creature
Enchanted creature gets +2/+2.
Threshold — As long as seven or more cards are in your graveyard, all creatures able to block enchanted creature do so.

Wild Mongrel

Discard a card: Wild Mongrel gets +1/+1 and becomes the color of your choice until end of turn.

Diligent Farmhand

{1}{G}, Sacrifice Diligent Farmhand: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
If Diligent Farmhand is in a graveyard, effects from spells named Muscle Burst count it as a card named Muscle Burst.